Today, I went out to eat. When I walked into the restaurant, a lady approached me and said she'd seat me soon. After a long wait, I saw that same lady leave. Then I realized she didn't actually work there and was just screwing with me. FML

That's irrelevant. 15 was simply asking when was the last time you went to a restaurant and immediately started wondering, "Gee, does that person asking my order/offering to seat me ACTUALLY work here?"
Personally, that thought's never even crossed my mind.

The only way I could see the wait being this long is if there was no seating required and it was a "seat yourself" time. A lot of the restaurants let you seat yourself during the day or during times it's not busy, and then at night or during the busier times they seat you. Maybe that was the case here? Still though, you'd think a waiter walking by or someone would notice op standing there and let them know they could seat themselves.